Multi-stage transmission for vehicle

ABSTRACT

A multi-stage transmission for a vehicle may include an input shaft, an output shaft, first to fourth planetary gear devices disposed between the input shaft and the output shaft to transmit rotary force, each of the first to fourth planetary gear devices having three rotary elements, and at least six shifting elements connected to the rotary elements of the planetary gear devices.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application No.10-2014-0177168, filed Dec. 10, 2014, the entire contents of which isincorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention generally relates to a multi-stage transmissionfor a vehicle and, more particularly, to a multi-stage transmissiontechnology able to realize as many shifting stages as possible using thefewest parts possible and the simplest configuration possible, therebyimproving fuel efficiency of a vehicle.

Description of Related Art

Recent rising oil prices have driven worldwide car manufacturers intounlimited competition to improve fuel efficiency. In addition, greatefforts have been made to reduce the weight and improve the fuelefficiency of engines based on a variety of techniques such asdownsizing.

Among methods that can be sought for transmissions equipped in vehiclesto improve fuel efficiency, there is a method allowing an engine tooperate at more efficient operation points using a multi-stagetransmission, thereby ultimately improving the fuel efficiency.

Such a multi-stage transmission allows an engine to operate in arelatively low RPM (revolutions per minute) range, thereby furtherimproving the quietness of a vehicle.

However, as the number of shifting stages of a transmission increases,the number of internal parts constituting the transmission alsoincreases. This may lead to undesirable effects instead, such as thereduced mountability and transfer efficiency and the increased cost andweight of the transmission. Therefore, in order to maximize the effectof improved fuel efficiency using the multi-staging of a transmission,it is important to devise a transmission structure able to realizemaximum efficiency using a relatively small number of parts and a simpleconfiguration.

The information disclosed in this Background of the Invention section isonly for enhancement of understanding of the general background of theinvention and should not be taken as an acknowledgement or any form ofsuggestion that this information forms the prior art already known to aperson skilled in the art.

BRIEF SUMMARY

Various aspects of the present invention are directed to providing amulti-stage transmission for a vehicle that is able to realize at leasteleven forward shifting stages and one reverse shifting stage with arelatively small number of parts and a simple configuration such that anengine may be operated at optimum operation points, thereby maximizingan improvement in the fuel efficiency of the vehicle, and the engine maybe operated more quietly, thereby improving the quietness of thevehicle.

According to various aspects of the present invention, a multi-stagetransmission for a vehicle may include an input shaft, an output shaft,first to fourth planetary gear devices disposed between the input shaftand the output shaft to transmit rotary force, each of the first tofourth planetary gear devices having three rotary elements, and at leastsix shifting elements connected to the rotary elements of the planetarygear devices, in which a first rotary element of the first planetarygear device may be selectively connected to a third rotary element ofthe second planetary gear device a third rotary element of the thirdplanetary gear device, a second rotary element of the first planetarygear device may be continuously connected to the input shaft andselectively connected to a first rotary element of the second planetarygear device, and a third rotary element of the first planetary geardevice may be continuously connected to a second rotary element of thesecond planetary gear device, the second rotary element of the secondplanetary gear device may be continuously connected to a first rotaryelement of the fourth planetary gear device and the third rotary elementof the second planetary gear device may be continuously connected to afirst rotary element of the third planetary gear device, the firstrotary element of the third planetary gear device may be selectivelyconnected to a second rotary element of the fourth planetary gear deviceand a second rotary element of the third planetary gear device may becontinuously connected to a third rotary element of the fourth planetarygear device, and the first rotary element of the fourth planetary geardevice may be installed to be fixable by one shifting element of the atleast six shifting elements, the second rotary element of the fourthplanetary gear device may be continuously connected to the output shaftand the third rotary element of the fourth planetary gear device may beinstalled to be fixable by another shifting element of the at least sixshifting elements.

The first planetary gear device, the second planetary gear device, thethird planetary gear device and the fourth planetary gear device may besequentially arranged along an axial direction of the input shaft andthe output shaft.

The first rotary element of the fourth planetary gear device may beinstalled to be fixable to a transmission case by means of a thirdclutch from among the at least six shifting elements, the third rotaryelement of the fourth planetary gear device may be installed to befixable to the transmission case by means of a fourth clutch from amongthe at least six shifting elements, and the remaining shifting elementsfrom among the at least six shifting elements form selective connectionstructures between the rotary elements of the planetary gear devices.

A first clutch from among the at least six shifting elements may form aselective connection structure between the second rotary element of thefirst planetary gear device and the first rotary element of the secondplanetary gear device, a second clutch from among the at least sixshifting elements may form a selective connection structure between thefirst rotary element of the third planetary gear device and the secondrotary element of the fourth planetary gear device, a fifth clutch fromamong the at least six shifting elements may form a selective connectionstructure between the first rotary element of the first planetary geardevice and the third rotary element of the second planetary gear device,and a sixth clutch from among the at least six shifting elements mayform a selective connection structure between the first rotary elementof the first planetary gear device and the third rotary element of thethird planetary gear device.

According to various aspects of the present invention, a multi-stagetransmission for a vehicle may include first to fourth planetary geardevices each having three rotary elements, six shifting elementsconfigured to selectively provide frictional force, and first to eighthrotary shafts connected to the rotary elements of the first to fourthplanetary gear devices, in which the first rotary shaft may be an inputshaft directly connected to a second rotary element of the firstplanetary gear device, the second rotary shaft may be directly connectedto a first rotary element of the first planetary gear device, the thirdrotary shaft may be directly connected to a third rotary element of thefirst planetary gear device, a second rotary element of the secondplanetary gear device and a first rotary element of the fourth planetarygear device, the fourth rotary shaft may be directly connected to afirst rotary element of the second planetary gear device, the fifthrotary shaft may be directly connected to a third rotary element of thesecond planetary gear device and a first rotary element of the thirdplanetary gear device, the sixth rotary shaft may be directly connectedto a third rotary element of the third planetary gear device, theseventh rotary shaft may be directly connected to a second rotaryelement of the third planetary gear device and a third rotary element ofthe fourth planetary gear device, the eighth rotary shaft may be anoutput shaft directly connected to a second rotary element of the fourthplanetary gear device, and the six shifting elements may include firstto sixth clutches, the first clutch may be disposed between the firstrotary shaft and the fourth rotary shaft, the second clutch may bedisposed between the fifth rotary shaft and the eighth rotary shaft, thethird clutch may be disposed between the third rotary shaft and atransmission case, the fourth clutch may be disposed between the seventhrotary shaft and the transmission case, the fifth clutch may be disposedbetween the second rotary shaft and the fifth rotary shaft, the sixthclutch may be disposed between the second rotary shaft and the sixthrotary shaft.

According to the present invention as set forth above, the multi-stagetransmission for a vehicle can realize at least eleven forward shiftingstages and one reverse shifting stage with a relatively small number ofparts and a simple configuration such that the engine may be operated atoptimum operation points, thereby maximizing an improvement in the fuelefficiency of the vehicle, and the engine may be operated more quietly,thereby improving the quietness of the vehicle.

It is understood that the term “vehicle” or “vehicular” or other similarterms as used herein is inclusive of motor vehicles in general such aspassenger automobiles including sports utility vehicles (SUV), buses,trucks, various commercial vehicles, watercraft including a variety ofboats and ships, aircraft, and the like, and includes hybrid vehicles,electric vehicles, plug-in hybrid electric vehicles, hydrogen-poweredvehicles and other alternative fuel vehicles (e.g., fuel derived fromresources other than petroleum). As referred to herein, a hybrid vehicleis a vehicle that has two or more sources of power, for example, bothgasoline-powered and electric-powered vehicles.

The methods and apparatuses of the present invention have other featuresand advantages which will be apparent from or are set forth in moredetail in the accompanying drawings, which are incorporated herein, andthe following Detailed Description, which together serve to explaincertain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an exemplary multi-stage transmissionfor a vehicle according to the present invention.

FIG. 2 illustrates an operation mode table of the exemplary multi-stagetransmission shown in FIG. 1.

It should be understood that the appended drawings are not necessarilyto scale, presenting a somewhat simplified representation of variousfeatures illustrative of the basic principles of the invention. Thespecific design features of the present invention as disclosed herein,including, for example, specific dimensions, orientations, locations,and shapes will be determined in part by the particular intendedapplication and use environment.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of thepresent invention(s), examples of which are illustrated in theaccompanying drawings and described below. While the invention(s) willbe described in conjunction with exemplary embodiments, it will beunderstood that the present description is not intended to limit theinvention(s) to those exemplary embodiments. On the contrary, theinvention(s) is/are intended to cover not only the exemplaryembodiments, but also various alternatives, modifications, equivalentsand other embodiments, which may be included within the spirit and scopeof the invention as defined by the appended claims.

Referring to FIG. 1 and FIG. 2, a multi-stage transmission for a vehicleaccording to an exemplary embodiment of the present invention includesan input shaft IN, an output shaft OUT, first to fourth planetary geardevices PG1, PG2, PG3 and PG4 disposed between the input shaft IN andthe output shaft OUT to transmit rotary force, each of the first tofourth planetary gear devices PG1 to PG4 having three rotary elements,and at least six shifting elements connected to the rotary elements ofthe first to fourth planetary gear devices PG1 to PG4.

A first rotary element S1 of the first planetary gear device PG1 isselectively connected to each of a third rotary element R2 of the secondplanetary gear device PG2 and a third rotary element R3 of the thirdplanetary gear device PG3. A second rotary element C1 of the firstplanetary gear device PG1 is continuously connected to the input shaftIN and selectively connected to the first rotary element S2 of thesecond planetary gear device PG2. A third rotary element R1 of the firstplanetary gear device PG1 is continuously connected to a second rotaryelement C2 of the second planetary gear device PG2.

The second rotary element C2 of the second planetary gear device PG2 iscontinuously connected to a first rotary element S4 of the fourthplanetary gear device PG4 and the third rotary element R2 of the secondplanetary gear device PG2 is continuously connected to a first rotaryelement S3 of the third planetary gear device PG3.

The first rotary element S3 of the third planetary gear device PG3 isselectively connected to a second rotary element C4 of the fourthplanetary gear device PG4 and a second rotary element C3 of the thirdplanetary gear device PG3 is continuously connected to a third rotaryelement R4 of the fourth planetary gear device PG4.

The first rotary element S4 of the fourth planetary gear device PG4 isinstalled to be fixable by one rotary element of the at least sixshifting elements, the second rotary element C4 of the fourth planetarygear device PG4 is continuously connected to the output shaft OUT andthe third rotary element R4 of the fourth planetary gear device PG4 isinstalled to be fixable by another rotary element of the at least sixshifting elements.

The first planetary gear device PG1, the second planetary gear devicePG2, the third planetary gear device PG3 and the fourth planetary geardevice PG4 are sequentially arranged along the axial direction of theinput shaft IN and the output shaft OUT.

The first rotary element S4 of the fourth planetary gear device PG4 isinstalled to be fixable to a transmission case CS by means of a thirdclutch CL3 from among the at least six shifting elements. The thirdrotary element R4 of the fourth planetary gear device PG4 is installedto be fixable to the transmission case CS by means of a fourth clutchCL4 from among the at least six shifting elements.

Therefore, the third clutch CL3 and the fourth clutch CL4 function asbrakes such that the first rotary element S4 and the third rotaryelement R4 of the fourth planetary gear device PG4 may be converted torotatable state or restrained state not to be rotated by means of theoperations of the third clutch CL3 and the fourth clutch CL4,respectively.

The other shifting elements from among the at least six shiftingelements are configured to constitute selective connection structuresbetween the rotary elements of the planetary gear devices.

Specifically, a first clutch CL1 from among the at least six shiftingelements forms a selective connection structure between the secondrotary element C1 of the first planetary gear device PG1 and the firstrotary element S2 of the second planetary gear device PG2. A secondclutch CL2 from among the at least six shifting elements forms aselective connection structure between the first rotary element S3 ofthe third planetary gear device PG3 and the second rotary element C4 ofthe fourth planetary gear device PG4. A fifth clutch CL5 from among theat least six shifting elements forms a selective connection structurebetween the first rotary element S1 of the first planetary gear devicePG1 and the third rotary element R2 of the second planetary gear devicePG2. A sixth clutch CL6 from among the at least six shifting elementsforms a selective connection structure between the first rotary elementS1 of the first planetary gear device PG1 and the third rotary elementR3 of the third planetary gear device PG3.

According to this embodiment, the first rotary element S1, the secondrotary element C1 and the third rotary element R1 of the first planetarygear device PG1 are a first sun gear, a first carrier and a first ringgear, respectively. The first rotary element S2, the second rotaryelement C2 and the third rotary element R2 of the second planetary geardevice PG2 are a second sun gear, a second carrier and a second ringgear, respectively. The first rotary element S3, the second rotaryelement C3 and the third rotary element R3 of the third planetary geardevice PG3 are a third sun gear, a third carrier and a third ring gear,respectively. The first rotary element S4, the second rotary element C4and the third rotary element R4 of the fourth planetary gear device PG4are a fourth sun gear, a fourth carrier and a fourth ring gear,respectively.

The multi-stage transmission for a vehicle configured as above may alsobe presented as follows.

Specifically, the multi-stage transmission for a vehicle according tothe present invention includes the first to fourth planetary geardevices PG1 to PG4 each having the three rotary elements; the sixshifting elements configured to selectively provide frictional force;and eight rotary shafts connected to the rotary elements of the first tofourth planetary gear devices.

Hence, from among the eight rotary shafts, the first rotary shaft RS1 isthe input shaft IN directly connected to the second rotary element C1 ofthe first planetary gear device PG1. The second rotary shaft RS2 isdirectly connected to the first rotary element S1 of the first planetarygear device PG1. The third rotary shaft RS3 is directly connected to thethird rotary element R1 of the first planetary gear device PG1, thesecond rotary element C2 of the second planetary gear device PG2 and thefirst rotary element S4 of the fourth planetary gear device PG4. Thefourth rotary shaft RS4 is directly connected to the first rotaryelement S2 of the second planetary gear device PG2. The fifth rotaryshaft RS5 is directly connected to the third rotary element R2 of thesecond planetary gear device PG2 and the first rotary element S3 of thethird planetary gear device PG3. The sixth rotary shaft RS6 is directlyconnected to the third rotary element R3 of the third planetary geardevice PG3. The seventh rotary shaft RS7 is the second rotary element C3of the third planetary gear device PG3 and the third rotary element R4of the fourth planetary gear device PG4. The eighth rotary shaft RS8 isthe output shaft OUT directly connected to the second rotary element C4of the fourth planetary gear device PG4.

In addition, from among the six shifting elements, the first clutch CL1is disposed between the first rotary shaft RS1 and the fourth rotaryshaft RS4. The second clutch CL2 is disposed between the fifth rotaryshaft RS5 and the eighth rotary shaft RS8. The third clutch CL3 isdisposed between the third rotary shaft RS3 and a transmission case CS.The fourth clutch CL4 is disposed between the seventh rotary shaft RS7and the transmission case CS. The fifth clutch CL5 is disposed betweenthe second rotary shaft RS2 and the fifth rotary shaft RS5. The sixthclutch CL6 is disposed between the second rotary shaft RS2 and the sixthrotary shaft RS6.

As set forth above, the multi-stage transmission for a vehicle accordingto the present invention including the four simple planetary geardevices and the six shifting elements realizes eleven forward shiftingstages and one reverse shifting stage according to the operation modetable as illustrated in FIG. 2. Since the multi-stage shifting stages ofeleven shifting stages can be embodied based on a relatively smallnumber of parts and a simple configuration, the multi-stage transmissionfor a vehicle can contribute to the improved fuel efficiency andquietness of a vehicle, thereby ultimately improving the marketabilityof the vehicle.

The foregoing descriptions of specific exemplary embodiments of thepresent invention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteachings. The exemplary embodiments were chosen and described in orderto explain certain principles of the invention and their practicalapplication, to thereby enable others skilled in the art to make andutilize various exemplary embodiments of the present invention, as wellas various alternatives and modifications thereof. It is intended thatthe scope of the invention be defined by the Claims appended hereto andtheir equivalents.

What is claimed is:
 1. A multi-stage transmission for a vehiclecomprising: an input shaft; an output shaft; first to fourth planetarygear devices disposed between the input shaft and the output shaft totransmit rotary force, each of the first to fourth planetary geardevices having three rotary elements; and at least six shifting elementsconnected to the rotary elements of the planetary gear devices, whereina first rotary element of the first planetary gear device is selectivelyconnected to a third rotary element of the second planetary gear deviceand a third rotary element of the third planetary gear device, a secondrotary element of the first planetary gear device is continuouslyconnected to the input shaft and selectively connected to a first rotaryelement of the second planetary gear device, and a third rotary elementof the first planetary gear device is continuously connected to a secondrotary element of the second planetary gear device, wherein the secondrotary element of the second planetary gear device is continuouslyconnected to a first rotary element of the fourth planetary gear deviceand the third rotary element of the second planetary gear device iscontinuously connected to a first rotary element of the third planetarygear device, wherein the first rotary element of the third planetarygear device is selectively connected to a second rotary element of thefourth planetary gear device and a second rotary element of the thirdplanetary gear device is continuously connected to a third rotaryelement of the fourth planetary gear device, and wherein the firstrotary element of the fourth planetary gear device is installed to befixable by one shifting element of the at least six shifting elements,the second rotary element of the fourth planetary gear device iscontinuously connected to the output shaft and the third rotary elementof the fourth planetary gear device is installed to be fixable byanother shifting element of the at least six shifting elements.
 2. Themulti-stage transmission according to claim 1, wherein the firstplanetary gear device, the second planetary gear device, the thirdplanetary gear device and the fourth planetary gear device aresequentially arranged along an axial direction of the input shaft andthe output shaft.
 3. The multi-stage transmission according to claim 2,wherein the first rotary element of the fourth planetary gear device isinstalled to be fixable to a transmission case by means of a thirdclutch from among the at least six shifting elements, wherein the thirdrotary element of the fourth planetary gear device is installed to befixable to the transmission case by means of a fourth clutch from amongthe at least six shifting elements, and wherein remaining shiftingelements from among the at least six shifting elements form selectiveconnection structures between the rotary elements of the planetary geardevices.
 4. The multi-stage transmission according to claim 3, wherein afirst clutch from among the at least six shifting elements forms aselective connection structure between the second rotary element of thefirst planetary gear device and the first rotary element of the secondplanetary gear device, wherein a second clutch from among the at leastsix shifting elements forms a selective connection structure between thefirst rotary element of the third planetary gear device and the secondrotary element of the fourth planetary gear device, wherein a fifthclutch from among the at least six shifting elements forms a selectiveconnection structure between the first rotary element of the firstplanetary gear device and the third rotary element of the secondplanetary gear device, and wherein a sixth clutch from among the atleast six shifting elements forms a selective connection structurebetween the first rotary element of the first planetary gear device andthe third rotary element of the third planetary gear device.
 5. Amulti-stage transmission for a vehicle comprising: first to fourthplanetary gear devices each having three rotary elements; six shiftingelements configured to selectively provide frictional force; and firstto eighth rotary shafts connected to the rotary elements of the first tofourth planetary gear devices, wherein the first rotary shaft is aninput shaft directly connected to a second rotary element of the firstplanetary gear device, the second rotary shaft is directly connected toa first rotary element of the first planetary gear device, the thirdrotary shaft is directly connected to a third rotary element of thefirst planetary gear device, a second rotary element of the secondplanetary gear device and a first rotary element of the fourth planetarygear device, the fourth rotary shaft is directly connected to a firstrotary element of the second planetary gear device, the fifth rotaryshaft is directly connected to a third rotary element of the secondplanetary gear device and a first rotary element of the third planetarygear device, the sixth rotary shaft is directly connected to a thirdrotary element of the third planetary gear device, the seventh rotaryshaft is directly connected to a second rotary element of the thirdplanetary gear device and a third rotary element of the fourth planetarygear device, the eighth rotary shaft is an output shaft directlyconnected to a second rotary element of the fourth planetary geardevice, and wherein the six shifting elements include first to sixthclutches, the first clutch is disposed between the first rotary shaftand the fourth rotary shaft, the second clutch is disposed between thefifth rotary shaft and the eighth rotary shaft, the third clutch isdisposed between the third rotary shaft and a transmission case, thefourth clutch is disposed between the seventh rotary shaft and thetransmission case, the fifth clutch is disposed between the secondrotary shaft and the fifth rotary shaft, the sixth clutch is disposedbetween the second rotary shaft and the sixth rotary shaft.
 6. Themulti-stage transmission according to claim 5, wherein the firstplanetary gear device, the second planetary gear device, the thirdplanetary gear device and the fourth planetary gear device aresequentially arranged along an axial direction of the input shaft andthe output shaft.
 7. The multi-stage transmission according to claim 5,wherein the first clutch is disposed to form a selective connectionbetween the second rotary element of the first planetary gear device andthe first rotary element of the second planetary gear device, the secondclutch is disposed to form a selective connection between the firstrotary element of the third planetary gear device and the second rotaryelement of the fourth planetary gear device, the fifth clutch isdisposed to form a selective connection between the first rotary elementof the first planetary gear device and the third rotary element of thesecond planetary gear device, and the sixth clutch is disposed to form aselective connection between the first rotary element of the firstplanetary gear device and the third rotary element of the thirdplanetary gear device.